As a cartridge mounted in an image formatting apparatus that adopts an electrophotographic system, there is known a photoreceptor cartridge which includes a photosensitive member and on which a developer cartridge accommodating developer therein can be detachably mounted.
As such a photoreceptor cartridge, for example, the following drum cartridge is proposed. The proposed drum cartridge includes: a lower housing on which a photosensitive drum and a transfer roller are mounted; and an upper housing on which a scorotron charger and a cleaning member are mounted. The upper housing is mounted on the lower housing so as to cover from above (see US 2006/245786A1, for example).